Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 31 Jul 2002 06:58:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 31 Jul 2002 06:58:35 -0400 Received: from sunny.pacific.net.au ([203.25.148.40]:28401 "EHLO sunny.pacific.net.au") by vger.kernel.org with ESMTP id ; Wed, 31 Jul 2002 06:58:35 -0400 From: "David Luyer" To: Cc: "'Alan Cox'" Subject: RE: Linux 2.4.19ac3rc3 on IBM x330/x340 SMP - "ps" time skew Date: Wed, 31 Jul 2002 21:01:45 +1000 Message-ID: <00b601c23881$a8dfa180$638317d2@pacific.net.au> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.3416 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Importance: Normal In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1643 Lines: 50 I wrote: > In Linux 2.4.19ac3rc3 on IBM x330/x340 SMP systems we're seeing this: > > luyer@praxis8:~$ ps auxwww | tail -1 > luyer 1025 0.0 0.0 1276 352 pts/2 S Aug06 0:00 tail -1 > luyer@praxis8:~$ date > Wed Jul 31 12:35:16 EST 2002 (UP systems are fine, SMP have this problem) Reason: luyer@praxis8:~$ ps --info 2>&1 | grep Hertz EUID=111 TTY=136,3 Hertz=50 procps is getting the hertz value wrong, it's computing it as: h = (unsigned long)( (double)jiffies/seconds/smp_num_cpus ); but we're only getting timer interrupts on CPU 0, and hence jiffies is only incrementing once per 100th of a second. luyer@praxis8:~/procps/procps-2.0.7.orig/proc$ cat /proc/interrupts CPU0 CPU1 0: 52459351 0 local-APIC-edge timer 1: 0 2 IO-APIC-edge keyboard 2: 0 0 XT-PIC cascade 24: 883655 863043 IO-APIC-level ips 26: 7 9 IO-APIC-level aic7xxx 27: 8 8 IO-APIC-level aic7xxx 28: 97880608 96542591 IO-APIC-level eth0 NMI: 0 0 LOC: 52456889 52456887 ERR: 0 MIS: 0 procps version is 2.0.7 (Debian 3.0). Where's the mistake -- should timer interrupts be on both CPUs (I think this is the problem), or is procps miscalculating Hz (seems less likely, someone would have noticed by now...)? David. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/